Cyanide-containing solutions are being used in a number of industrial processes which include metal plating processes and metallurgical processes for the recovery of precious metals, especially gold. These and other processes are the source of cyanide-containing waste solutions which must be treated for the removal of cyanide prior to discharge into the environment.
Many methods have been developed for the removal of cyanide from waste waters and solutions. The removal processes include such operations as dialysis, electrodialysis, membrane electrolysis and electrochemical oxidation and reduction with and without the addition of alkali metal chloride, alkali metal oxychloride or chlorine. The methods disclosed in the prior art are generally directed either to the concentration and recovery of cyanide or to the destruction of cyanide in solution. Either type of method has a serious disadvantage. The concentration and recovery methods leave a residual solution that still contains cyanide, and such residual solutions can not be discharged to the environment. The destruction methods remove substantially all cyanide without recovery thereby losing cyanide that must be replaced in the process wherein cyanide is used.